Return-Path: From: Jeffy Chen To: linux-bluetooth@vger.kernel.org Cc: Brian Norris , Douglas Anderson , Johan Hedberg , Peter Hurley , Jeffy Chen , Johan Hedberg , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" , Marcel Holtmann , Gustavo Padovan Subject: [PATCH v4 2/3] Bluetooth: cmtp: fix possible might sleep error in cmtp_session Date: Tue, 14 Feb 2017 08:55:24 +0800 Message-Id: <1487033725-7208-2-git-send-email-jeffy.chen@rock-chips.com> In-Reply-To: <1487033725-7208-1-git-send-email-jeffy.chen@rock-chips.com> References: <1487033725-7208-1-git-send-email-jeffy.chen@rock-chips.com> List-ID: It looks like cmtp_session has same pattern as the issue reported in old rfcomm: while (1) { set_current_state(TASK_INTERRUPTIBLE); if (condition) break; // may call might_sleep here schedule(); } __set_current_state(TASK_RUNNING); Which fixed at: dfb2fae Bluetooth: Fix nested sleeps So let's fix it at the same way, also follow the suggestion of: https://lwn.net/Articles/628628/ Signed-off-by: Jeffy Chen Reviewed-by: Brian Norris Remove unnecessary memory barrier before wake_up_* functions. --- Changes in v3: Add brian's Reviewed-by. Changes in v2: None net/bluetooth/cmtp/core.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c index 9e59b66..1152ce3 100644 --- a/net/bluetooth/cmtp/core.c +++ b/net/bluetooth/cmtp/core.c @@ -280,16 +280,16 @@ static int cmtp_session(void *arg) struct cmtp_session *session = arg; struct sock *sk = session->sock->sk; struct sk_buff *skb; - wait_queue_t wait; + DEFINE_WAIT_FUNC(wait, woken_wake_function); BT_DBG("session %p", session); set_user_nice(current, -15); - init_waitqueue_entry(&wait, current); add_wait_queue(sk_sleep(sk), &wait); while (1) { - set_current_state(TASK_INTERRUPTIBLE); + /* Ensure session->terminate is updated */ + smp_mb__before_atomic(); if (atomic_read(&session->terminate)) break; @@ -306,9 +306,8 @@ static int cmtp_session(void *arg) cmtp_process_transmit(session); - schedule(); + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } - __set_current_state(TASK_RUNNING); remove_wait_queue(sk_sleep(sk), &wait); down_write(&cmtp_session_sem); @@ -393,7 +392,7 @@ int cmtp_add_connection(struct cmtp_connadd_req *req, struct socket *sock) err = cmtp_attach_device(session); if (err < 0) { atomic_inc(&session->terminate); - wake_up_process(session->task); + wake_up_interruptible(sk_sleep(session->sock->sk)); up_write(&cmtp_session_sem); return err; } @@ -431,7 +430,11 @@ int cmtp_del_connection(struct cmtp_conndel_req *req) /* Stop session thread */ atomic_inc(&session->terminate); - wake_up_process(session->task); + + /* Ensure session->terminate is updated */ + smp_mb__after_atomic(); + + wake_up_interruptible(sk_sleep(session->sock->sk)); } else err = -ENOENT; -- 2.1.4